Drying apparatus



3 Sheets-Sheet 1 AZLAM.

Oct. 25, 1949. F. w. KosTER E'rAL DRYING APPARATUS Filed April 19, 1945Oct. 25, 1949. F. w. KosrER Erm.

DRYING APPARATUS 3 Sheets-Sheet 2 Filed April 19, 1945 uws/vrou.

0a 25.1949. F. w. STER mL y DRYING APPARATUS Filed April 1S, 1945 3Sheets-Sheet 3 2d. md. uw

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Patented Oct. 25, 1949 2,485,609 'DBYING APPARATUS Frederick W. Koster,Wallingford, and Louis A. Oberly, Swarthmore, Pa., assignors to AmericanViscose Corporation, Wilmington, poration of Delaware Del., a cor-Application April 19, 1945, Serial No. 589,200

4 claims. l

This invention relates to apparatus for drying parcels of lamentarymaterial and the like, such as wound packages of rayon.

It is an object of the present invention to provide an improved dryingapparatus utilizing the dielectric characteristics of the materials tobe dried for developing the heat internally thereof in which the parcelsto be dried are carried by a foraminous support which is moved in acyclical path along a portion of which a high frequency electric eld isdeveloped and maintained, while at the same time passing a current ofheated gaseous medium, such as air, upwardly through the foraminoussupport and above the parcels being dried to facilitate the removal ofmoisture vaporized by the dielectric heating and to prevent condensationof the vaporized moisture on adjacent surfaces of the apparatus, such asthe electrodes, their supports, and the housing through which theforaminous support moves. Other objects and advantages ofthe inventionwill be apparent from the drawing and the description thereofhereinafter.

In the drawing illustrative of the invention,

Figure 1 is a plan view, with part of the housing removed of oneembodiment of the invention;

Figure 2 is an elevation of the embodiment of Figure 1;

Figure 3 is a plan view, with part of the housing removed, of amodification;

Figure 4 is a cross-sectional elevation of the embodiment of Figure 3;

Figure 5 is a cross-sectional elevation of another modification;

Figure 6 is a plan view of a modification with the roof of the housingremoved; and

Figure '1 is a cross-sectional elevation of a modification of Figure 5.

As shown in Figures 1 and 2, an annular foraminous belt or platform 2,such as of openmesh metallic screen material is rotated about its axisby the supporting conical rolls 3 which are driven by the pinions 4arranged inside the annular belt which mesh with the annular gear -5carried by the central shaft 6 mounted for rotation by means of a motor1 therebelow. The shaft carries in spider-like arrangement a pluralityof outwardly extending arms 8 which have projections 9 thereof hinged atpoints I0 and II. Individual electrodes I2, preferably of foraminousmaterial, such as metallic screening, are suspended pivotally from theouter ends of the respective projections from the arms of the spider, sothat the electrodes are arranged above the annular foraminous belt 2.The upper portion of 2 the shaft 6 carrying the spider 5 is of metal butis insulated by an intermediate section I3 from the lower portion of theshaft extending to the motor 1. A brush I4 bears against the uppermetallic portion of the shaft and is connected by a lead I5 to one poleI'6 of a high frequency oscillator I1, such as a radio frequencyoscillator. The arms, projections and suspensions to the individualelectrodes are all of metallic construci tion, so that the brush servesto connect each of such electrodes with the sam'e pole of theoscillator. The other pole I8 of the oscillator is preferably groundedand the annular foraminous belt is also grounded at I9 so it willconstitute a cooperating electrode with respect to the upper individualelectrodes. Beneath the annular belt 2 there is arranged a duct 20,preferably of annular shape having discharge openings 2I in the uppersurface thereof. One end of the duct is connected to a chamber 22adapted to receive a heating element 23, such as a steam coil, electriccoil or the like, so that air entering the duct is heated thereby. A fan24 may be provided in the chamber to force the air into the duct. Ahousing 25 is provided about the assembly and the roof may slopeupwardly to the center thereof to which the discharge duct 26 may beconnected to a fan 21 for inducing a draft therethrough. The housing isprovided with an opening 28 in the peripheral wall, so that the annularbelt is accessible to an operator for introducing and removing theparcels of material to be dried. Preferably the opening is of suchheight as to allow plenty of room for the size of the parcels 3| to behandled and it is provided with a back wall 29 just behind the annularbelt which may be supported by a bottom and ceiling walls extendinginwardly from the lower and upper edges of the opening. A stationary cam30 is arranged above the charging opening in the path of the hingedprojections 9 from which the electrodes I2 are pivotally suspended sothat as they are brought into proximity to the opening, the upperelectrodes are lifted from the parcels 3| and proceed over the ceilingof the opening and then descend into contact with the parcels beyond thecharging opening. In this fashion, the operator is protected from anysubstantial influence of the high frequency electric eld.

In operation of the embodiment of Figures 1 and 2, the motor rotates theshaft which effects travel of the annular foraminous belt and theelectrodes at the same speed in a cyclical path, part of which extendsthrough the charging opening. As the annular foraminous supportlteristics of the oscillator may be adjusted to give any desired heatingeilect internally of the parcels depending upon the particular naturethereof. The temperature of the air which is forced upwardly through theforaminous support is also controlled in accordance with the material under i consideration. For example, where wound packages, such as cakesof regenerated cellulose filaments, 4such as those obtained fromviscose, are being dried, the temperature of the air may be from about140 to 170 F., whereas the temperature developed internally of the cakeby the electric field may be about the same as that of the air orhigher, such as up to substantially 212 F. The passage of the heated airthrough the housing, which may be insulated advantageously, serves toprevent condensation on the walls thereof and on the upper electrodesand the suspensions thereof, thereby preventing drippings back upon theparcel being dried, conserving heat and increasing the uniformity ofdrying efl'ect.

As shown in Figures 3 and 4, a similar housing 32 having a similarcharging opening 33 is provided but the foraminous belt 34 is dividedinto sections which are connected together by insulating transverse ribs3l. As shown more particularly in Figure4, the annular carriage iscomprised of a plurality of supporting brackets 36 connected together byannular angle bars 31 and provided with rollers 38 operating upon anannular track 39. A spider I carried by a shaft 4l driven by the motorI2 with bevel gears 43 and Il is secured to the annular carriage forrotating it about its axis. The carriage may be composed entirely ofinsulating materials, or at least sufllcient to provide for theelectrical separation or insulation oi' the several sections of metallicscreen 45 or equivalent foraminous web, which, as shown, is wrappedabout the inner and outer peripheries of the upper surface of thecarriage. The lower insulated segments or sections of the foraminoussupporting web constitute lower electrodes and a plurality ofoscillators 46 may be arranged about the periphery of the an-A nularcarriage except for the vicinity of the charging opening of the housing.Metallic belts 41 are connected to one pole of a correspondingoscillator and driven by small motors 48 serve to connect the foraminoussupporting web adjacent the respective portions of the periphery of theannulus to distinct oscillators. The other pole of the severaloscillators may be grounded. An upper foraminous web 49 is suspendedfrom the roof of the housing 32 a suilicient distance above the carriageto allow ample room for passage of the parcel l! that is grounded. rlhesection of 'this 'upper forarninous electrode adjacent the chargingopening 33 may be and is preferably omitted. Agia annular duct 5l isarranged below carriage and openings 52 in its upper surface todischarge upwardly. As in the first embodiment, a chamber 53 is providedadjacent the entrance to the duct and contains a heating coil 5:3 and afan 55 or blower 'to force air into the duct. At one or more pointsabout the annular duct, humidifiers 56 are arranged therein. Thesehumidiflers may be controlled to impart a predetermined relativehumidity to the air that is circulated past the parcels to be dried, Aninternal cone 61 is formed within the housing to provide a more or lessflaring annulus for discharging the air and the evaporated moisturecontained therein through a central discharge duct Il which may again beprovided with a suction fan or blower l0.

This embodiment of the invention has the advantage of providing forindependent control oi' the various'stages of drying. Thus, at the firststage of drying, the relative humidity of the heated air forced past theparcel being dried and the electrical characteristics of the oscillatormay be preselected independently of those provided in successive stagesof the drying path or cycle. Thus, the drying may be started while inthe presence of high humidity heated air and at successive stages, therelative humidity may be progressively lower. At the same time, theelectrical characteristics of the oscillators may be progressivelychanged to eii'ect a higher heating rate in successive stages of thecycle until a predetermined moisture content of the parcels is obtained,after which the heating eii'ect may be progressively decreased. Ifdesired, instead ot providing a single air inlet and heating chamber forthe entire duct, a plurality of such may be arranged thereabout, aseparate heater and fan serving to supply the heated air adjacent eachdistinct portion of the cycle. Thus, the temperature as well as therelative humidity and the dielectric heating eiect at any given stagecan be controlled independently of those characteristics at succeedingstages of the drying cycle.

Figure 5 shows a modification in which a longitudinal housing isprovided having a duct 6| at the bottom for receiving air which isheated by a coil 82 and blown by the fan 63 set in a chamber to one sideof the apparatus and cornmunicating with one end, the charge end, of theduct. The duct is provided with openings 64 in its upper surface toallow the air to ilow upwardly. A foraminous metallic belt 65 is drivenby rolls 86 which may be provided with sprockets 6l and is in turndriven by the motor 68 and interconnecting chain 69. The foraminous beltsystem is grounded to serve as one electrode in the high frequencysystem and suitable rolls 'l0 having sprockets 1| at their ends serve tosupport the upper course of the foraminous belt as it travels from oneend to the other of the housing. The chains 12 operated by the endsprockets 61 engage the sprockets at the end of the small supportingrolls and serve to drive them at substantially the same linear speed asthe foraminous belt. The width of the belt 65 is approximately the widthof the housing but extends outwardly therefrom at each end and thehousing has an opening 13 at each ond above the belt to allow theentrance and discharge of the parcels 14 to be dried. A metallic chainl5 is driven by end sprockets 'i6 and carries individual electrodes llat spaced intervals therealong. Guide rollers 78 may be provided tosupport the upper source of the chain and the chain may be driven fromthe same motor as the ioraminous belt by means of the chain i9 so thatboth the electrode-carrying chain and the foraminous belt travel at thesame speed. One pole 80 of the radio frequency oscillator 82 iselectrically connected to the electrede-carrying chain and the other maybe grounded. The roof of the housing 60 may be sloped upwardly towardthe discharge end of the apparatus and a duct 8| may be connected to thehighest portion thereof and may be proannees vided with a ian forwithdrawing air and moisture therefrom. e

' heated air along the bottom thereof as in Figure is provided with anendless belt Il of foraminous character as in Figure 5 for supportingthe parcels to be dried. The supporting ioraminous belt Il isv drivenbut is not intended in this embodiment to form a pole for the highfrequency current. Instead, the upper electrodes and driving structureare omitted and electrodes 85 are disposed substantially vertically atopposite sides of the path of the parcels within the housing 83. Theelectrodes on one side may be connected to one pole of an oscillatorwhile those of the other side are connected to the opposite pole.Alternatively. a separate oscillator may be provided for each pair ofelectrodes and alternate oscillators are disposed on opposite sides ofthe housing, so that the electrode of each pair which has the shortestlead to its oscillator is positioned alternately on opposite sides ofthe series of pairs.

Figure 7 shows a modification of Figure 5, in which the upper individualelectrodes are replaced by an endless foraminous belt 81 similar to thatconstituting the lower electrode. The lower course of the upper belt maybe allowed to droop into contact withy the parcels. so that it reststhereon as they proceed through the housing.

The present invention is adaptable to the drying of parcels ofillamentary material which merely contain moisture and also to suchparcels as may have been treated with other conditioning agents whetherin the presence of water as a solvent or in the presence of an organicsolvent of volatile character. For example, the apparatus may be used todry rayon to which a soap solution has been applied, with the object ofleaving a small amount of soap upon the iibers as a conditioning agent.Again, an aqueous emulsion or a solution in an organic solvent of oils,soaps, fats, dyes, pigments or waxes may have been applied. Again, theconditioning medium may be one which undergoes condensation or curing toa nal insoluble condition, examples of such being urea formaldehyde,resins, melamine resins, or rubber and synthetic rubber dispersions.

The present invention lends itself readily to procedures in which theremoval of solvent and/or reaction between components of theconditioning medium, or between one or more components of theconditioning medium and a textile material is effected in separatestages of a multiple-stage process. For example, for many purposes itmay be desirable to eiect merely a removal of solvent at a relativelylow temperature until a deilnite solvent content is obtained and thenilnish the removal of solvent and simultaneous reaction at a hightemperature for a short time. This procedure, in which a negligibleamount of reaction is eil'ected during the preliminary stage and thereaction and ilnal drying are both accomplished in a short time in, theilnal stage is particularly advantageous when the conditioning mediumcontains one or more components which, during the treatment with heat.undergo a change to an insoluble condition such that 'removal oi' thebalance of the solvent by diiiusion through the insoluble product isgreatly hindered or almost completely prevented.

While preferred embodiments have been described, it is to be understoodthat they are merely illustrative of the invention, and that changes andvariations may be made herein without departing from the spirit andscope as deiined by the appended claims.

We claim:

l. Apparatus for drying parcels of iilamentary material and the likecomprising a foraminous belt electrode for supporting the parcel to bedried, means for moving the electrode through a cyclical path, a housingsubstantially enclosing the electrode except for openings providedtherein adjacent the positions for charging and discharging the parcelsto be dried, a plurality of electrodes arranged above the path, meansfor moving the latter electrodes along a portion of the path with thefirst electrode at substantially the same speed, means for lowering theupper electrodes as they pass beyond the charging position, means forelevating the upper electrodes in advance of the discharge position, andmeans for forming a high frequency electrostatic ileld between the lowerand upper electrodes respectively.

2. Apparatus for drying parcels of illamentary material and the likecomprising a foraminous belt electrode for supporting the parcel to bedried, means for moving the electrode through a cyclical path, a housingsubstantially enclosing the electrode except for openings providedtherein adjacent the positions for charging and discharging the parcelto be dried, means arranged beneath at least a portion of the path fordirecting a gaseous medium upwardly therethrough, a plurality ofelectrodes arranged above the path, means for moving the latterelectrodes along a portion of the path with the first electrode atsubstantially the same speed, means for lowering the upper electrodes asthey pass beyond the charging position, means for elevating the upperelectrodes in advance of the discharge position, and means for forming ahigh frequency electrostatic field between the lower and upperelectrodes respectively.

3. Apparatus for drying parcels of iilamentary material and the likecomprising an annular foraminous electrode for supporting the parcel tobe dried, means for rotating the electrode about its axis through acyclical path, a housing substantially enclosing the electrode exceptfor openings provided therein adjacent the positions for charging anddischarging the parcels to be dried, means arranged beneath at least aportion of the path for directing a gaseous medium upwardlytherethrough, a plurality of electrodes arranged annularly above thepath, means for moving the latter electrodes along a portion of the pathwith the rst electrode at substantially the same speed, means forlowering the upper electrodes as they pass beyond the charging position,means for elevating the upper electrodes in advance of the dischargeposition, and means for forming a high frequency electrostatic fieldbetween the lower and upper electrodes respectively.

4. Apparatus for drying parcels of filamentary material and the likecomprising an annular vforaminous electrode for supporting the parcel tobe dried, means for rotating the electrode about its axis through acyclical path, a housing substantially enclosing the electrode exceptfor openings provided therein adjacent the positions for charging anddischarging the parcels to be dried, said openings being opposed to eachother and a shielding arrangement comprising a bottom wall, back wall.and ceiling provided between the two openings, means arranged beneath atleast a portion of the path for directing a gaseous medium upwardlytherethrough. a plurality of electrodes arranged annularly above thepath, means for moving the latter electrodes along a portion of the pathwith the rst electrode at substantially the same speed, means forlowering the upper electrodes as they pass beyond the charging position,means for elevating the upper electrodes in advance of the'dischargeposition, and means for forming a high frequency electrostatic eldbetween the lower and upper electrodes respectively, means forimpressing a high frequency electrostatic iield across the belts, andmeans for directing a gaseous medium upwardly through the belts.

LOUIS A. OBERLY.

FREDERICK W. KOSTER.

Nunxber Name 327,198 Sargent Sept. 29. 1395 811,306 Lorimer Jan. 30,1906 1,476,424 Sargent Dec. 4. 1923 1,626,766 Tompkins May 3, 19272,042,145 Darrah May 28, 1936 2,231,457 Stephen Feb. i1, 1941 2,263,681Hart, Jr Nov. 25, 1941 2,275,431 Hart, Jr., et al Mar. i0, 19422,291,807 Hart, Jr Aug. 4, 1942 2,325,652 Bierwirth Aug. 3, 19432,390,572 Brabander Dec. 11, 1945 2,403,800 Hoyler July 9, 19492,408,434 Mann et al Oct. 1, 1946 2,428,615 Brown Oct. 7, 1947

